I have been using Windows Live Custom Domains since probably 2009. Basically this is Outlook.com/Hotmail with a custom domain. I believe it would continue to work for the foreseeable future but I am tired of not being able to add new accounts since the product was put in coast mode 6-8 years ago.
So, I am nearing a cutover to my own email server. This is running a common Postfix/Dovecot/Roundcube setup on a virtual machine, with SMTP2Go as an outbound relay/smarthost since I don't want to bother with requesting my residential cable IP get removed from block-lists (I believe it is a straightforward and possible process though). I currently have a secondary domain setup and working. In the next month or so I will get the main domain moved, including a couple family members. Backups are Duplicity to Backblaze B2, and yeah if my home server setup completely imploded and I was looking at days of downtime I would implement Fastmail or similar.
Synology has what seems to be a turn-key mail system, if you have or want a Synology.
https://sive.rs/ti (Tech Independence step-by-step) would be a good way to go, I think.